The intro foreshadows Colin Robinson's death by showing his full portrait with lit candles in front of it, just like a memorial display or shrine.
Of course vampires don't turn their Familiars. They lose a valuable servant and have to get a new one. Besides, familiarity breeds contempt.
Nandor is excited to use glitter to look like a "Twilight" vampire. The idea disgusts Guillermo. Of course Guillermo hates Twilight, because everything about classic vampires, even their weaknesses, is part of their dark gothic coolness to him. Naturally, Nandor loves Twilight, a fantasy in which vampires can go out into the sunlight and are loved by humans. It's the difference between someone who romanticizes classic vampires, and someone who has actually been one for a thousand years.
The documentary crew being allowed to film Vampiric Council business makes a lot of sense the moment they show the film's vampires, since they already set a precedent for bringing filmmakers into supernatural business and being responsible for their safety.
Of course the vampires made the Staten Island Coven into the Vampire Council. They've already failed to kill them many times, and it's just easier. The Vampire Council is shown to not actually care about justice but appearances. They were even ready to let them go and just blame Guillermo.
When the entertainment at Nadja's nightclub continues to fall apart and the crowd starts to become enraged, it is the currently child-like Colin Robinson that wins over the crowd with old show tunes. Apart from coming back around to the idea of accepting the new Colin for who he is, that this won over the crowd makes some sense. Many of those songs had broad appeal during their day, and it's likely that many of the vampires in attendance were around when these songs were fresh.
In 4x07, Nadja mentions that Lazslo dislikes her favorite film, Mamma Mia!, as it reminds him of all the illegitimate children he fathered as a human. This makes his strong averse reaction to Guillermo getting him an ancestry report in 1x10 make more sense.
Nadja being able to subdue and hypnotize Guillermo's family members checks out when considering how they stack up compared to Guillermo. While, yes, his family outnumbers Nadja and has a natural predisposition towards killing vampires, that's all they have against her as first-timers who likely never encountered vampires prior to this episode. Meanwhile, Guillermo has years of honed experience killing vampires and a built-up hypnosis immunity to back him up, the latter being something his family crucially lacks going up against Nadja.
When Freddie leaves Guillermo to date the clone Nandor made of him, it brings to mind the concept of "Boyfriend Twins." A very real and oft-parodied phenomenon among gay men where two partners will be virtually identical in appearance, body type, fashion tastes, etc.
The situations in "Collaboration" and "The Wellness Center" are practically reverses of each other. In "Collaboration", Nandor rescues Guillermo from a group of humans led by a human pretending to be a vampire. In "The Wellness Center", Guillermo rescues Nandor from a group of vampires led by a vampire pretending to be human.
After Guillermo becomes a vampire, he's unable to feed off of an innocent person. It may seem strange that he's unable to bring himself to do so despite having killed numerous vampires over the last few seasons, something he himself brings up. Except that every vampire he's killed was either by accident (the Baron) or he was defending someone (himself, the housemates, the Mosquito Collectors' Club) from those vampires. The people he was supposed to feed on were innocent and had done nothing to harm him.
Energetic teenaged Colin turns into old vampiric Colin Robinson after he read Colin's' diary about his detailed day-to-day life. Given how Colin Robinson is, it was so boring, it sucked all the energy out of teenaged Colin, making him an Energy Vampire again.
In 2x08, it's implied Celeste's con lasted around two weeks. While some of her workarounds, like claiming that sleeping on couches and vaping blood are new vampire trends, are acceptable, no mention is made of how Celeste would have faked the real supernatural abilities of vampires. This first implies that none of her "familiars" asked about her powers, which would be quite unlikely, considering cool powers are the main appeal of becoming a vampire. But even then, every vampire we see uses powers like bat form and super speed quite often and casually. So it would be particularly egregious that Celeste wouldn't be doing any of it, when familiars know how real vampires behave.
In 'Go Flip Yourself' it turns out that Bran Daltry, one of the Show Within a Show's hosts, is actually Simon the Devious in disguise and the staff responsible for renovating the depicted homes are his crew of vampires. However, clips shown from other episodes show both Daltrys showing off the renovations outside in broad daylight-which, while the human Toby would have no problems, of course would not be possible for Simon/Bran to do and, assuming the production staff are all his crew, would also not be possible to shoot (admittedly, this is more easy to work around assuming there are in fact some human members of the production crew, but the issue with Simon remains).
Now that the vampires' ghosts have moved on, we know there is absolutely nothing waiting for them should they die again. A death that goes beyond death.
Marwa's entire plot line is a slow motion train wreck of Fridge Horror. One of Nandor's many wives during his human life, she is resurrected in season four, hundreds of years after her death and the deaths of all her family. She is resurrected with the rest of his wives so that he can choose one to remarry in the present day. He finally chooses Marwa (after re-deathing the rest of the wives at the first sign of any minor flaw), and proceeds to use his Djinn wishes to alter her appearance on a whim without her knowledge or consent. The night before their wedding, Nandor wishes for Marwa to like everything he likes so that she will go along with his plans for how to do the wedding. It's later revealed that she had been having second thoughts about marrying Nandor, but that the wish essentially brainwashed her into going through with it. Future episodes establish that this wish has effectively removed her free will and turned her into a Yes-Man for Nandor, seemingly without any awareness on her part. Finally, in "Freddie," Nandor, tired of her as a result of the submissive personality he imposed, wishes for her to turn into a complete physical and mental copy of Guillermo's boyfriend Freddie, and Marwa herself completely disappears. Nandor never undoes the wish, reasoning that Marwa-cum-Freddie seems happier as a completely different person, and sends clone!Freddie off to travel the world. Marwa is not seen again for the rest of the season. Even worse, the exact mechanics of the wish are left unclear: Did she simply stop existing, with the new Freddie taking her place? Is it an intense form of brainwashing to give her a different personality, complete with a new body? Is she somehow trapped in her own mind, aware of what's going on but unable to do anything?
'Go Flip Yourself', while largely comedic, does raise some concerns when you think about the implications of the reveal that Bran is actually Simon and most of the workers who renovate the homes are members of his crew. ANYONE who agreed to be on the show invited a veritable horde of vampires into their homes. Who is to say that some portion-or even all-the hapless humans who invited the Daltry brothers to renovate their homes didn't end up drained?
